1. Field of the Invention
This invention relates to earth drilling with rock bits that utilize air as the circulating fluid, and especially to filtering means used to provide filtered air to the bearings of such bits.
2. Description of the Prior Art
Some earth drilling systems use air to cool the bit and carry earth cuttings from the bottom of the hole to the surface. Water is often injected into the air pumped to the bit. A variety of apparatus and methods have been previously suggested for separating the water from the air pumped to the rock bits to isolate the bearings from detrimental water while permitting filtered air to cool the bearings.
U.S. patent of J. G. Jackson, U.S. Pat. No. 3,094,175, issued June 18, 1973, discloses the use of a centrifugal separator with a spiralled flight or flange in pursuit of the above objects. A similar separator is disclosed in the U.S. patent of W. M. Crook, U.S. Pat. No. 2,329,745, issued Sept. 21, 1943, to separate grit from the liquid often circulated in oil and gas well drilling. Another spiralled centrifugal separator is disclosed in the U.S. patent of Dysart, U.S. Pat. No. 3,788,408, issued Jan. 29, 1974.
The use of individual tubes, sometimes combined with a diffuser, has been previously disclosed as for example in the above patent to Dysart. Radial vane separators have been used in other arts. Air has been cleaned by one such separator for the carburetor intakes of tractors to minimize the induction of dust and other contaminants into engines.